<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style type="text/css">
        .talk_con{
            width:600px;
            height:500px;
            border:1px solid #666;
            margin:50px auto 0;
            background:#f9f9f9;
        }
        .talk_show{
            width:580px;
            height:420px;
            border:1px solid #666;
            background:#fff;
            margin:10px auto 0;
            overflow:auto;
        }
        .talk_input{
            width:580px;
            margin:10px auto 0;
        }
        .whotalk{
            width:80px;
            height:30px;
            float:left;
            outline:none;
        }
        .talk_word{
            width:420px;
            height:26px;
            padding:0px;
            float:left;
            margin-left:10px;
            outline:none;
            text-indent:10px;
        }        
        .talk_sub{
            width:56px;
            height:30px;
            float:left;
            margin-left:10px;
        }
        .atalk{
           margin:10px; 
        }
        .atalk span{
            display:inline-block;
            background:#0181cc;
            border-radius:10px;
            color:#fff;
            padding:5px 10px;
        }
        .btalk{
            margin:10px;
            text-align:right;
        }
        .btalk span{
            display:inline-block;
            background:#ef8201;
            border-radius:10px;
            color:#fff;
            padding:5px 10px;
        }
    </style>
    <script type="text/javascript">      
    // 写出对应功能代码
    window.onload = function() {
        // 按钮控制文本的发送
        var oBtn = document.getElementById("talksub");
        // alert(oBtn);
        // 输入框控制文本
        var oInput = document.getElementById("talkwords");
        // alert(oInput.value);
        // 选择框控制说话对象
        var oSelect = document.getElementById("who");
        // alert(oSelect.value);
        // 选择框控制说话内容
        var oOption = document.getElementsByTagName("option");
        // alert(oOption.length);
        // alert(oOption[0].textContent)       
        // 控制显示的对话内容
        var oDiv = document.getElementById("words");
        // alert(oDiv.length);
        // alert(oDiv.innerHTML);
        var words;
        oBtn.onclick = function() {
            // alert(oInput.value);
            // if(oInput.value == "") {
            //     alert("no words!")
            // }
            if(oInput.value != "") {
                // alert(oInput.value)
                if(oSelect.value == 0) {
                    words = "<div class='atalk'><span>" + oOption[0].textContent + oInput.value + "</span></div>";
                }
                else if(oSelect.value == 1){
                    words = "<div class='btalk'><span>" + oOption[1].textContent + oInput.value + "</span></div>";
                }
                oDiv.innerHTML = oDiv.innerHTML + words;
            }
            // alert(words);
        }
    }
    </script>
</head>
<body>
    <div class="talk_con">
        <div class="talk_show" id="words">
            <div class="atalk"><span>A说：吃饭了吗？</span></div>
            <div class="btalk"><span>B说：还没呢，你呢？</span></div>
        </div>
        <div class="talk_input">
            <select class="whotalk" id="who">
                <option value="0">A说：</option>
                <option value="1">B说：</option>
            </select>
            <input type="text" class="talk_word" id="talkwords">
            <input type="button" value="发送" class="talk_sub" id="talksub">
        </div>
    </div>
</body>
</html>